Of snakes and faces: an evolutionary perspective on the psychology of fear.

Snakes and faces are unique stimuli because they are deeply grounded in evolutionarily shaped behavior systems. Snakes are the prototypical stimulus in a predatory defense system promoting escape from predators, which prepares primates for efficient processing, attentional priority, and rapid fear acquisition to snakes and other stimuli related to predation. The social submissiveness system plays a similar role on the social arena by promoting yielding to dominant individuals without jeopardizing the protection of the group. Supporting these theoretical propositions, empirical data from a research program spanning four decades demonstrate enhanced fear conditioning to snakes and threatening faces compared to neutral stimuli, as well as fast nonconscious processing of, and prioritized attention to, snakes and threatening faces. Human brain-imaging data show that these effects are mediated by an extensive fear-network centering on the amygdala.